Researchers from the Harbin Institute of Technology, with colleagues from the Beijing University of Technology and the University of Wisconsin Milwaukee, have synthesized tin chalcogenide (SnSe0.5S0.5) nanoplates for use as Li-ion anodes.
In a paper published in the Journal of Power Sources, they reported that the as-prepared of SnSe0.5S0.5 exhibits an outstanding discharge specific capacity of up to 1144 mAh g−1 at 0.1 A g−1 after 100 cycles and 682 mA h g−1 at 0.5 A g−1 after 200 cycles with a high coulombic efficiency (CE) of 98.7%. Even at a high current density of 5 A g−1, this anode material delivers a specific capacity of 473 mAh g−1.
A full cell with an NCM cathode and SnSe0.5S0.5 anode, under a current density of 0.5 A g−1, delivered a lithiation capacity of 1111 mA h g−1 and after 50 cycles, the full cell maintained a lithiation capacity of 535 mA h g−1 with a coulombic efficiency of ∼98%.
Graphite, a widely used anode material for LIBs, is not suitable for the requirement of high capacity due to a low theoretical capacity of 372 mA h g−1. Thus, it is extremely important to develop new anode materials for batteries with high energy density. Silicon is one of the numerous alternative anode materials but, despite a high theoretical capacity, shows serious volume expansion (> 300%) and low electric conductivity which impedes its success in extensive application. Tin, as a result of an alloying reaction with Li, delivers a high theoretical gravimetric capacity of 994 mA h g−1 with the additional merits of low cost and toxicologically and consequently is considered one of the most promising anode materials for lithium ion batteries. However, the principal remaining challenge is to reduce the volume change (260%) during cycle process, as this is believed to cause large internal stress and destroy the integrity of electrode structure during cycling.
In order to overcome this disadvantage, many strategies have been proposed in recent years including surface modification, novel design structure and morphology, nano-sized particles and nanoporous materials to improve the structural stability. Various types of tin-based compounds have also been investigated to improve the performance as anode materials for LIBs.
… In this study, we successfully designed and synthesized a Sn-based chalcogenide (SnSe0.5S0.5) through a facile and fast polyol-method followed by low temperature heating to obtain a high-performance anode material for LIBs.—Tang et al.
The researchers determined that there are two main reasons behind the excellent electrochemical performance:
The unique three-dimensional nanoplate stacking structure of SnSe0.5S0.5 facilitates electronic/ionic diffusion and conversion reaction;
The synergism of Se and S elements provide a larger layer space and better conductivity, which is benefit to the process of lithiation and delithiation, and also to accommodate the volume change of tin-based materials.
Qiming Tang, Heng Su, Yanhui Cui, Andrew P. Baker, Yanchen Liu, Juan Lu, Xiaona Song, Huayu Zhang, Junwei Wu, Haijun Yu, Deyang Qu (2018) “Ternary tin-based chalcogenide nanoplates as a promising anode material for lithium-ion batteries,” Journal of Power Sources, Volume 379, Pages 182-190 doi: 10.1016/j.jpowsour.2018.01.051.